A Thin Film Transistor-Liquid Crystal Display (TFT-LCD) is to change orientation of liquid crystal molecules by using changes in intensity of an electric field sandwiched between upper and lower substrates, so as to control intensity of light transmittance to display an image. In general, a complete liquid crystal display panel must have a backlight module, a polaroid, a TFT substrate (a lower substrate), a Color Filter (CF) substrate (an upper substrate) and a liquid crystal molecule layer filled in a box formed by the upper and lower substrates. There are a large number of pixel electrodes on the TFT substrate, and turning on and off voltage as well as magnitude of voltage on the pixel electrode is controlled by a gate electrode signal connected with a transverse scanning signal line and a source electrode signal connected with a longitudinal data line. The orientation of liquid crystal molecules is controlled by changes in intensity of an electric field between the common electrode and the pixel electrode. A storage capacitor may be formed between the common electrode (Vcom) line and the pixel electrode on the TFT substrate, so as to maintain state of the liquid crystal molecules before a next signal is coming.
At present, the TFT substrate may adopt a dual gate design, which can effectively reduce a number of IC joints of the data line, to achieve an effect of reducing cost. Generally, a panel of a dual-gate design usually has a common electrode line parallel to a scanning signal line and a common electrode line parallel to a data line, so that an aperture ratio of pixel is low.